DOE OSTI2020
Er3(RuSi3)4 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to twelve Si2- atoms to form distorted ErSi12 cuboctahedra that share corners with four equivalent ErSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with four equivalent ErSi12 cuboctahedra, edges with two equivalent RuSi7 hexagonal pyramids, and faces with four equivalent ErSi12 cuboctahedra. There are a spread of Er–Si bond distances ranging from 2.97–3.22 Å. In the second Er3+ site, Er3+ is bonded to twelve Si2- atoms to form ErSi12 cuboctahedra that share corners with four equivalent ErSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with eight equivalent ErSi12 cuboctahedra, and faces with four equivalent RuSi7 hexagonal pyramids. There are four shorter (3.02 Å) and eight longer (3.09 Å) Er–Si bond lengths. There are two inequivalent Ru+3.75+ sites. In the first Ru+3.75+ site, Ru+3.75+ is bonded in a 5-coordinate geometry to five Si2- atoms. There are one shorter (2.32 Å) and four longer (2.41 Å) Ru–Si bond lengths. In the second Ru+3.75+ site, Ru+3.75+ is bonded to seven Si2- atoms to form distorted RuSi7 hexagonal pyramids that share corners with six ErSi12 cuboctahedra, corners with four equivalent RuSi7 hexagonal pyramids, edges with two equivalent ErSi12 cuboctahedra, an edgeedge with one RuSi7 hexagonal pyramid, and faces with two equivalent ErSi12 cuboctahedra. There are a spread of Ru–Si bond distances ranging from 2.36–2.52 Å. There are four inequivalent Si2- sites. In the first Si2- site, Si2- is bonded in a 2-coordinate geometry to three Er3+, two Ru+3.75+, and four Si2- atoms. There are a spread of Si–Si bond distances ranging from 2.47–2.68 Å. In the second Si2- site, Si2- is bonded in a 2-coordinate geometry to three Er3+, two Ru+3.75+, and four Si2- atoms. There are one shorter (2.47 Å) and one longer (2.63 Å) Si–Si bond lengths. In the third Si2- site, Si2- is bonded in a 1-coordinate geometry to four equivalent Er3+, one Ru+3.75+, and four Si2- atoms. In the fourth Si2- site, Si2- is bonded in a 9-coordinate geometry to two equivalent Er3+, three equivalent Ru+3.75+, and four Si2- atoms.